In a detergent such as a shampoo or a body soap, a so-called conditioning agent is incorporated to improve the smoothness in washing or in combing or passing fingers through the hair after the washing, or the smoothness, flexibility, silky texture or other textures of the hair after drying. For example, it is known to incorporate cationic hydroxyethyl cellulose, cationic guar gum, a dimethyl diallyl ammonium chloride/acrylamide copolymer as a conditioning agent to a shampoo.
The shampoo having cationic hydroxyethyl cellulose or the like incorporated is good in finger-combing in rinsing, but after drying, the hair is likely to present a coarse or stiff texture. To overcome such a drawback, it has been studied, for example, to incorporate an oil or to use a surfactant in combination. Particularly, it is known to incorporate silicone oil, whereby the texture after drying will substantially change (e.g. JP-A-2003-212733 (U.S. 2003-0170197)).
Further, the conditioning agent is required to be adsorbed to the hair and accordingly, an amino acid-modified cationic polymer has been proposed as a conditioning agent which has stickiness or greasiness reduced while maintaining a proper adsorption property and which maintains a conditioning effect without being washed off in rinsing (e.g. JP-A-2003-034704).